1. Field
The present invention relates to a magnetic recording medium and a method of manufacturing the same.
2. Description of the Related Art
Recently, in magnetic recording media incorporated into hard disk drives (HDDs), there is an increasing problem of disturbance of enhancement of track density due to interference between adjacent tracks. In particular, a serious technical subject is reduction of a fringe effect of a field from a write head.
To solve such a problem, a discrete track recording-type patterned medium (DTR medium), for example, has been proposed in which recording tracks are physically separated by processing a ferromagnetic layer. The DTR medium can reduce a side erase phenomenon, i.e., erasing information of an adjacent track in writing, and a side read phenomenon, i.e., reading out information of an adjacent track in reading, making it possible to enhance the track density. Therefore, the DTR medium is expected as a magnetic recording medium capable of providing a high recording density.
In reading from and writing to a medium like a DTR medium with an irregular surface with a flying head, it is required to reduce surface irregularity of the DTR medium so as to bring about stable flying of the head. In an existing DTR medium, in order to form grooves separating adjacent tracks completely, for example, a protective film with a thickness of about 5 nm and a magnetic recording layer with a thickness of about 20 nm in total of about 25 nm are removed. On the other hand, the designed flying height of the flying head is about 10 nm. Accordingly, it has been carried out to fill the grooves with a nonmagnetic material so as to flatten the medium surface for ensuring flying stability of the head. However, filling the grooves with the non-magnetic layer to flatten the medium surface increases the number of manufacturing processes, which in turn increases the cost and also reduces the yield.
Under the circumstances, methods of modifying the ferromagnetic layer corresponding to non-recording regions between tracks into the non-magnetic layer have been used without introducing the irregular structure to the medium (see U.S. Pat. No. 6,841,224; Jpn. Pat. Appln. KOKAI Publication No. 5-205257; and U.S. Pat. No. 6,168,845). However, when the ferromagnetic layer in the non-recording regions are merely modified into the non-magnetic layer without introducing the irregular structure to the medium, boundaries between the magnetic patterns forming tracks and the non-magnetic layer are easily fluctuated, which may cause noise. Thus, how the magnetic properties of the non-recording regions can be modified while preventing the modification of the magnetic properties of the tracks becomes a problem.